Concat () function or alternative solution in mysql query - php

Question

I am trying to add a character before/after value in mysql query. but I can't make it work.
This is the part that doesn't work in my case:
$query = "select CONCAT ('.', DuRpt) as DuRpt, DaRpt from DDtb order by DATE DESC";
You can see the full code below. Any ideas why it doesn't work or can I get an alternative solution, please. thanks.
<div class="container">
<div class="left">
<?php
include ("etc/config.php");
$query = "select concat ('.', DuRpt) as DuRpt, DaRpt from DDtb order by DATE DESC";
$result = mysqli_query($link, $query);
if (!$result) {
$message = 'ERROR:' . mysqli_error($link);
return $message;
} else {
$i = 0;
echo '<form name="select" action="" method="GET">';
echo '<select name="mySelect" id="mySelect" size="44" onchange="this.form.submit()">';
while ($i < mysqli_field_count($link)) {
$meta =
mysqli_fetch_field_direct($result, $i);
echo '<option>' . $meta->name . '</option>';
$i = $i + 1;
}
echo '</select>';
echo '</form>';
}
?>
</div>
<div>
<?php
if(isset($_GET['mySelect'])) {
$myselect = $_GET['mySelect'];
$sql = "SELECT `$myselect` as mySelect from DDtb order by DATE DESC";
$result = mysqli_query($link, $sql);
if ($result->num_rows > 0) {
$table_row_counter = 3;
echo '<table>';
while($row = $result->fetch_assoc())
{
$table_row_counter++;
if ($table_row_counter % 30 == 1) {
echo '</table>';
echo '<table>';
}
echo "<tr><td>" . $row["mySelect"] . "</td></tr>";
}
}
}
echo '</table>';
mysqli_close($link);
?>
</div>
</div>

Answer 1

For the 2nd half of your code, you can do this:
note you won't need to concat anything in your initial query
if(isset($_GET['mySelect'])) {
// configure every option here, if there's not pre/postfix, use a blank string
$prepostfixes = [
'DuRpt' => ['.', '.'],
'DaRpt' => ['', ''],
];
$myselect = $_GET['mySelect'];
if (!isset($prepostfixes[$myselect])) {
die ('Unknown Select'); // this will prevent sql injection
}
$sql = "SELECT `$myselect` as mySelect from DDtb order by DATE DESC";
$result = mysqli_query($link, $sql);
if ($result->num_rows > 0) {
$table_row_counter = 3;
echo '<table>';
$prefix = $prepostfixes[$myselect][0];
$postfix = $prepostfixes[$myselect][1];
while($row = $result->fetch_assoc())
{
$table_row_counter++;
if ($table_row_counter % 30 == 1) {
echo '</table>';
echo '<table>';
}
echo "<tr><td>" . $prefix . $row["mySelect"] . $postfix . "</td></tr>";
}
}
}

Answer 2

Just update your code and remove the duplicate of DuRpt from it.
$query = "select concat ('.', DuRpt) as DuRpt from DDtb order by DATE DESC";